Fuel filler cap

ABSTRACT

A fuel filler cap is provided with a nozzle engagement that can engage with the nozzle of a fuel pump, enabling it to be unscrewed by turning the fuel pump nozzle. The nozzle engagement structure is designed so that it can only engage with a particular size of fuel pump nozzle, resulting in a fuel filler cap that cannot be removed with a fuel pump nozzle of a different size and goes some way toward preventing the misfuelling of cars equipped with the fuel filler cap. A second fuel filler cap is provided with a lid that may be freely rotated on the body. The cap may be activated by engaging an appropriate nozzle with the nozzle engagement means, causing the lid to become firmly attached to the cap and therefore operable for unscrewing the cap.

This invention relates to fuel filling systems; more particularly fuelfiller caps for vehicles and especially to a fuel filler cap forpreventing the misfuelling of cars.

In recent years, common rail diesel engines have improved to the pointwhere they offer comparable performance to petrol engines, withoutlosing their fuel efficiency advantage over the same. As such, dieselcars have seen a surge in popularity, particularly amongst company carusers. There are currently estimated to be ten million small dieselvehicles in the UK alone, with that number apparently bound to rise inthe near future.

A recurring problem with diesel cars is that their drivers maymistakenly fill them with petrol, rather than diesel, when at the fuelstation. With modern common rail diesel engines, misfuelling is a muchmore significant problem than it was with older diesel engines, aspetrol does not have the same lubricating qualities as diesel and canlead to thousands of pounds of damage being caused to the fuel system,in particular the fuel injectors and pumps. Even if the driver of thecar realises his mistake before starting the engine, it may be necessaryto drain the fuel system, which is itself relatively expensive, andinconvenient.

Similarly, petrol cars can be misfuelled with diesel fuel, which canalso cause engine damage. Petrol vehicles are misfuelled less frequentlyas modern unleaded petrol cars have a fuel filling aperture that issmaller than a diesel nozzle. This size discrepancy came about whencatalytic converters and unleaded fuel were introduced. Catalyticconverters would be damaged by the use of four-star fuel, so the size ofthe aperture and fuel pump nozzle for catalytic converter equipped carsand unleaded fuel were reduced to prevent the misfuelling of thevehicles. Nonetheless, misfuelling then of four-star petrol intounleaded petrol vehicles still occurred then as with the misfuelling ofdiesel fuel into unleaded petrol vehicles today. This may occur, forexample, when a user does not properly insert a fuel pump nozzle intothe fuel filling aperture, or alternatively when fuelling a vehicleusing a small, portable container.

In the case of company cars and leased cars misfuelling can be morecommon than with privately owned cars, as the driver of such cars may beunused to filling their car with diesel and fill the car with petrolaccidentally. This is a particular problem for the leasing or fleetmanaging company, as without prior agreement they may be liable for themechanical cost of repairing a car if it is operated using the wrongfuel. As such, a market for a device to prevent the misfuelling of carshas come about.

The main difficulty in developing such a device is that, by UK law,unleaded petrol nozzles have a smaller diameter (21 mm) than diesel fuelnozzles (25 mm). This is useful for preventing the misfuelling of petrolvehicles, but makes it difficult to restrict the entry of an unleadednozzle into the larger hole designed for the diesel nozzle. Furthermore,a small proportion of drivers manage to force the larger diesel fuelnozzle into the fuel filling aperture of a petrol car, meaning that thecurrent differences in size are apparently insufficient to prevent thistype of misfuelling in all cases.

Previous attempts to prevent misfuelling of cars include simplewarnings, such as prominent stickers, or the electronic warning deviceDiesel Guard®, which emits an audible announcement to fill the car withdiesel whenever the fuel filler cover is opened. However, a sticker candisfigure the looks of a car if stuck to the outside, and a car thataudibly demands diesel at the filling station can be embarrassing.Furthermore, both of these devices are warnings and as such do notactually prevent the misfuelling—stickers can come off a car, and thebatteries in an electronic device can be exhausted, rendering eitherdevice useless. As such, there is a need for a device that actuallyprevents filling a vehicle with the wrong fuel.

According to a first aspect of the invention there is provided a fuelfiller cap comprising a body for fitting in a fuel filling aperture; ahandle rotatably coupled to the body; coupling means for selectivelycoupling the handle to the body for rotating the body by rotating thelid; and a trigger for activating the coupling means.

Preferably, the fuel filler cap comprises nozzle discrimination meansfor discriminating between nozzles having different properties, whereinthe trigger is associated with the nozzle discrimination means for beingactivated by an appropriate nozzle. This allows the handle to be firmlycoupled to the body via the coupling means when an appropriate nozzleactivates the trigger associated with the nozzle discrimination means.

Preferably, the nozzle discrimination means comprises a circular channelhaving appropriate dimensions for receiving a nozzle, and the trigger islocated in the bottom of the channel for being activated by a nozzleentering the channel. This means that only a nozzle of appropriatedimensions can reach the trigger.

Preferably, the trigger comprises a face oriented so that it facestowards the top of the channel, the face being sloped for movinglaterally under a camming action when pressed by a nozzle entering thechannel. This provides a simple and robust activation of the triggerthat can be used in activating the coupling means.

Preferably, said coupling means comprises an annular ratchet member andan arm for selectively engaging with the annular ratchet member. Thisprovides a reliable mechanism for selectively coupling the handle to thebody.

Preferably, the cap further comprises a resilient member for biasing thearm towards the annular ratchet member; wherein: the trigger is moved bya nozzle engaging with the nozzle discrimination means; the armcomprises a head for engaging with the trigger; the trigger and the headbeing arranged so that when they are engaged the arm is not engaged withthe annular ratchet member; further wherein: the movement of the triggercaused by the nozzle causes the trigger to disengage from the arm,allowing the arm to move towards the ratchet member.

According to a second aspect of the invention there is provided a fuelfiller cap, comprising nozzle engagement means for engaging with a fuelpump nozzle, the fuel pump nozzle including a sensing port.

Preferably, a torque applied to the fuel pump nozzle, when engaged tothe nozzle engagement means, is transferred to the fuel filler capthrough the nozzle engagement means. This results in a fuel filler capthat can be unscrewed by turning the fuel pump nozzle engaged with it.

Preferably, the nozzle engagement means further comprises sensing portengagement means for engaging with the sensing port of the fuel pumpnozzle, such that the torque transferred from the fuel pump nozzle tothe fuel filler cap is transferred through the sensing port and sensingport engagement means. This provides a simple way to transfer torquefrom a UK standard fuel pump nozzle to the fuel filler cap.

Advantageously, the fuel filler cap further comprises a threaded sectionfor screwing into a fuel filling receptacle, the screwing motion beingaround an axis of rotation; wherein the nozzle engagement meanscomprises a head extending substantially along the axis of rotation,distal to the threaded section, for fitting inside the fuel pump nozzle.

Optionally, the head is a substantially cylindrical projection from thefuel filler cap having an axis that generally coincides with the axis ofrotation. Such a head lacks the exposed edges of an annular head thatmay be damaged by a mis-aligned fuel pump nozzle.

Optionally, the head is a substantially annular projection from the fuelfiller cap having an axis that generally coincides with the axis ofrotation. Such a head is lighter than a cylindrical head.

Advantageously, the sensing port engagement means comprises one or moreindentations in the axially directed sides of the head for accommodatingthe sensing port and engaging with the side of the sensing port when thefuel pump nozzle is turned. This provides a simple mechanism forengaging the sensing port and transferring the torque.

Optionally, the sensing port engagement means comprises one or moreinterruptions in the axially directed sides of the head foraccommodating the sensing port and engaging with the side of the sensingport when the fuel pump nozzle is turned. This is an alternativemechanism for engaging the sensing port and transferring the torque.

Optionally, the sensing port engagement means further comprises a postfor fitting inside the sensing port of the fuel pump nozzle.

Alternatively, the head may comprise two or more resiliently mountedmembers, such that at least one member is depressed on engaging with afuel pump nozzle for creating sensing port engagement means foraccommodating the sensing port and engaging with the side of the sensingport when the fuel pump nozzle is turned. This provides a head thatdynamically forms sensing port engagement means when engaged with thefuel pump nozzle.

Alternatively, the head and sensing port engagement means may comprisean elongate projection, the edges of the projection being adapted forengaging with the side of the sensing port when the fuel pump nozzle isturned. This is a simple and lightweight engagement structure with alarge arc through which it can be first engaged with a fuel pump nozzle.

Preferably, the head is located in a recess in the fuel filler cap suchthat the head and fuel filler cap define a substantially axial recessinto the fuel filler cap for accepting the fuel pump nozzle. This meansthat the head is not exposed and is less likely to be damaged.

Preferably, the head is mounted on ratchet means such that when engagedto the fuel pump nozzle, the fuel pump nozzle does not need to turnthrough a full circle in order to turn the fuel filler cap.

Preferably, the fuel filler cap further comprises ratchet means orientedto provide purchase in one direction for screwing the cap into a fuelfilling receptacle. This means that the fuel filler cap can be screwedinto the fuel filling receptacle without the fuel pump nozzle afterfuelling.

Optionally, the ratchet means comprise two or more exposed handles forturning by hand. This provides a simple and robust mechanism to screwthe fuel cap into the fuel filling receptacle.

Optionally, the fuel filler cap further comprises an exposed cover thatcovers and is complementary to the ratchet means for providing a fuelfiller cap that can be screwed by hand into the fuel filling receptacle.Such an exposed cover makes it harder to unscrew the fuel filler cap byhand, as it does not provide purchase in such a direction.

According to a third aspect of the invention, there is provided a nozzleengagement structure for attaching to a fuel filler cap comprising thenozzle engagement structure of any one of claims 1 to 13.

According to a fourth aspect of the invention, there is provided a keyfor engaging with a fuel filler cap, the key having substantially thesame cross section as a fuel pump nozzle.

According to a fifth aspect of the invention, there is provided a methodfor removing a fuel filler cap from a fuel filling receptacle using afuel pump nozzle, the fuel filler cap comprising nozzle engagementmeans; the method comprising engaging the fuel pump nozzle with thenozzle engagement means; and turning the fuel pump nozzle to remove thefuel filler cap.

Embodiments of the invention will now be described, by way of example,with reference to the drawings in which:

FIG. 1 is a schematic cross section of a fuel pump nozzle;

FIG. 2 is a schematic perspective view of a fuel filler cap having aring-shaped nozzle engagement structure in accordance with theinvention;

FIG. 3 is a schematic perspective view of a fuel filler cap having a capbody shaped to allow turning in only one direction in accordance withthe invention;

FIG. 4 is a schematic perspective view of a fuel filler cap having arecessed nozzle engagement structure in accordance with the invention;

FIG. 5 is a schematic perspective view of a fuel filler cap having arecessed nozzle engagement structure having multiple sensing portengagement holes in accordance with the invention;

FIG. 6 is a schematic perspective view of a fuel filler cap having asolid, protruding nozzle engagement structure in accordance with theinvention;

FIG. 7 is a schematic perspective view of a fuel filler cap having across-shaped nozzle engagement structure in accordance with theinvention;

FIG. 8 is a schematic perspective view of a fuel filler cap having aninterrupted ring nozzle engagement structure with a further protrusionfor fitting inside the sensing port;

FIG. 9 is a schematic perspective view of a fuel filler cap having aspring-mounted segmented nozzle engagement structure;

FIG. 10 is a schematic perspective view of a fuel filler cap having a“single blade” nozzle engagement structure;

FIG. 11 is a perspective view of a fuel cap according to an embodimentof the invention;

FIG. 12 is a plan view of the fuel cap shown in FIG. 11 with its lidremoved, exposing the internal mechanism;

FIG. 13 is a plan view of an arm according to an embodiment of theinvention;

FIG. 14 is a plan view of a locking ring according to an embodiment ofthe invention;

FIG. 15 is an exploded perspective view of a button, arm and lockingring according to an embodiment of the invention;

FIG. 16 is a plan view of the fuel cap as shown in FIG. 12 with itsmechanism in the unlocked state; and

FIG. 17 is a plan view of the fuel cap as shown in FIG. 16 with themechanism activated.

The embodiments described below are explained in relation to a removablefuel filler cap for cars. The caps described are adapted to prevent themisfuelling of diesel vehicles with unleaded petrol. However, theprinciples described may readily be adapted for use in other filler capson other vehicles, or any other device that needs fuel such as agenerator, a fuelled lawn mower, chainsaw etc. The principles describedmay also be readily adapted for use in fuel filler caps adapted toprevent the misfuelling of, for example, unleaded petrol poweredvehicles. The present embodiments are described based on the sizes andassignment of sizes of fuel pump nozzles as correct at the time offiling. The principles described may be readily adapted should the sizesof such nozzles change. Furthermore, in the event of other fuels withdifferent nozzle configurations or sizes being used, the principlesdescribed may be adapted for use with them. The principles described arebased on engagement with a fuel pump nozzle having certain dimensionsand not limited to engaging diesel fuel nozzles and rejecting unleadedpetrol nozzles, or engaging unleaded petrol nozzles and rejecting dieselnozzles.

In this document, the term nozzle is used to describe the nozzle of afuel pump such as might be found at a petrol station, motorway servicestation or otherwise.

In normal use, to fill a car's fuel tank, the nozzle is inserted into afuel filling aperture which comprises a channel that leads to the fueltank. This fuel filling aperture is normally closed with a fuel fillercap which screws into the fuel filling aperture. This screwing actionmay require a number of turns of the fuel filler cap, or alternativelyonly an incomplete turn. The fuel filler cap may further be covered by afuel filler cover that may serve to disguise the fuel filler aperture,fuel filler cap and associated indentation into the body of the car. Theterm nozzle engagement structure is used in this document to refer to astructure that can engage with a nozzle.

The shape of fuel pump nozzles is standardised by legislation in the UKand elsewhere. FIG. 1 shows a schematic cross section of a typical fuelpump nozzle 2. The nozzle 2 comprises a nozzle body 4 that encloses anozzle channel 6. Nozzle body 4 has an outer diameter of 21 mm in thecase of a nozzle for unleaded petrol, and 25 mm in the case of a nozzlefor diesel or leaded petrol. These values are the ideal values, andthere may of course be some small variation between nozzles. The innerdiameter of the nozzle in these cases is approximately 16.5 mm and 19.5mm respectively.

This difference between those sizes of the unleaded petrol nozzle anddiesel nozzle provides a way of differentiating between the two and wasoriginally introduced to prevent diesel fuel being introduced intopetrol vehicles equipped with catalytic converters. Although a fuelfilling aperture large enough for a diesel nozzle cannot easily excludethe smaller unleaded petrol nozzle, a structure can be designed suchthat it can only engage a diesel nozzle and not an unleaded petrolnozzle. Such a structure can be achieved by having a head that fitsinside nozzle channel 6 of a diesel nozzle, but is too large to fitinside nozzle channel 6 of an unleaded petrol nozzle. This structure maybe a singular, large protrusion, or be a head consisting of a pluralityof smaller members that cannot all fit inside an unleaded petrol nozzlesimultaneously. Similarly, a nozzle engagement structure may be designedfor engaging with an unleaded petrol nozzle, which would be too small toengage properly with a diesel nozzle. However, such a head would stillfit inside a diesel nozzle, so it may be preferable to locate the headin a recess that is too small to permit the entry of a diesel nozzle sothat the head is not able to engage with the nozzle.

However, such a structure, whether the head comprises a single member ora plurality thereof, is not suitable for use in a fuel filling apertureas by design it protrudes into fuel nozzle channel 6 and hence reducesthe area through which fuel can be pumped. Furthermore, it would becomplicated to design a suitable structure for retrofitting intovehicles as fuel filling apertures vary greatly between car models andmanufacturers.

Fuel pump nozzle 2 further comprises a sensing port 8, again bylegislation. It is this port that is used to detect when the fuel tankis full, and hence to stop pumping fuel. This is achieved by applying avacuum to sensing port 8; when fuel travels into the sensing port thepump is cut off in a manner that is not material to the invention underdiscussion and hence is not described here. Sensing port 8 comprises asensing port body 10 that encloses a sensing port channel 12. As shownin FIG. 1, sensing port channel 12 is partly defined by sensing portbody 10, and partly by nozzle body 4, leaving the exterior of nozzlebody 4 unaffected by the presence of sensing port 8. In a diesel fuelnozzle, sensing port 8 has an outer diameter of approximately 7.5 mm.This can also be described as a radial protuberance into nozzle channel6 of approximately 5 mm from the inner edge of nozzle body 4, and acircumferential extension along the outside of nozzle body 4 ofapproximately 10 mm. In unleaded petrol nozzles, the outer diameter andprotuberance into nozzle channel 6 are typically similar. In this case,the circumferential extension along the outside of nozzle body 4 isapproximately 8.5 mm.

It is this sensing port 8 that allows the fuel filler cap shown in FIGS.2 to 10 to work. Sensing port 8 is a protuberance into the nozzlechannel 6, which provides a point that can engage with the previouslymentioned head designed for the fuel pump nozzle 2. This engagementallows the item comprising the structure to be turned by turning fuelpump nozzle 2. As such, by incorporating such a structure (be it asingle head or head comprising a plurality of members) into a fuelfiller cap, a diesel nozzle can be used to unscrew the fuel filler capwhere an unleaded petrol nozzle could not. This is a similar arrangementto that of a bolt and spanner. The fuel pump nozzle 2 with its sensingport 8, which constitutes a structure for transferring torque, may belikened to a spanner for engaging with the head; the head which iscomplementary to the fuel pump nozzle 2 transfers torque to the rest ofthe fuel filler cap in a similar manner as the head of a bolt.

Similarly, a nozzle engagement structure for engaging with an unleadedpetrol nozzle can be designed that fits inside a petrol nozzle, but istoo small to engage with the sensing port 8 of a diesel nozzle.Alternatively, the nozzle engagement structure may be in a recess in afuel filler cap, the recess having a diameter that prevents the entry ofa diesel nozzle.

Referring now to FIG. 2, a fuel filler cap 14 is provided according to afirst embodiment of the invention. Fuel filler cap 14 comprises athreaded section 16 for fitting to the fuel filler aperture of a car inthe usual way. This threaded section may comprise any number of threadsdepending on the application and the fuel filling aperture it isdesigned to be complementary to. Furthermore, in the case of a fuelfiller cap that requires only a fraction of a turn to screw into a fuelfilling aperture, the threaded section may comprise only short inclinedprojections or indentations that serve the function of a thread.Attached to the threaded section 16 is cap body 18. This may be providedwith ridges or otherwise in order to facilitate gripping it for removalor replacement. Threaded section 16 and cap body 18 may be separate,removably joined components, or may be separate sections of the samecomponent. The distinction between them may not be as clear as is shownin FIG. 2.

Fuel filler cap 14 further comprises a nozzle engagement structure 20.In this embodiment, nozzle engagement structure or head 20 protrudesfrom cap body 18. It is in the form of a protruding ring or annulushaving an interruption for engaging with the sensing port of a nozzle.For engaging with a diesel fuel pump nozzle, the outer diameter of thering is between 17.5 mm and 19.5 mm, and preferably between 18 mm and 19mm, and more preferably 18.5 mm. Because of its size, nozzle engagementstructure 20 is too large to fit inside the nozzle of an unleaded petrolfuel pump, and as such cannot engage with it. However, when the sensingport of a diesel nozzle is aligned with the interruption of nozzleengagement structure 20, the nozzle fits over engagement structure 20and can then be used to turn fuel filler cap 14, and so can be used tounscrew the nozzle. In order to properly accommodate the sensing port ofa diesel nozzle, the interruption in nozzle engagement structure 20 isat least 7.5 mm in terms of the circumferential gap (measured at theouter circumference of engagement structure 20), assuming an outerdiameter of engagement structure 20 of 18.5 mm.

In the case that nozzle engagement structure is for engaging with anunleaded petrol nozzle, it is not likely that an interrupted ring alonewill be sufficient to exclude a diesel nozzle—any ring that fits insidea petrol nozzle will also fit inside a diesel nozzle and may, to someextent, permit the fuel filler cap 14 to be turned by the nozzle. Assuch, it is preferable to locate such a ring in a recess, as describedabove and in more detail below. For engaging with an unleaded petrolfuel pump nozzle, the outer diameter of the ring is between 12 mm and16.5 mm, and preferably between 14 mm and 16.5 mm, and more preferably15.5 mm. Exceptionally, a ring with a diameter of less than 12 mm maywork, but it will not engage the sensing port unless it is somehowforced towards it and will thus have a more complicated operation. Inorder to accommodate the sensing port of an unleaded petrol nozzle, theinterruption in the ring is preferably at least 8 mm, measured as aboveand assuming an outer diameter of the ring of 15.5 mm.

Nozzle engagement structure 20 provides a simple test for whether theappropriate fuel pump nozzle has been selected. Although there isnothing stopping somebody unscrewing the fuel filler cap 14 by grippingcap body 18, unscrewing (or starting to unscrew) the fuel filler cap 14using the fuel pump nozzle is a simple behaviour to learn.Alternatively, fuel filler cap 14 may be designed such that the face ofcap body 18 is flush with the fuel filler aperture when secure, meaningthat a pump nozzle must be used at least to start unscrewing the fuelfiller cap 14. A disadvantage of this approach, however, is that a fuelpump nozzle must be used to replace the fuel filler cap 14 as well asremove it.

In order to provide drainage for fuel that might be present in the fuelpump nozzle when it is used to unscrew or replace fuel filler cap 14,the cap 14 may further comprise one or more drainage hole 22 to allowfuel to flow away. This might lead into the fuel filler aperture of thecar when the fuel filler cap 14 is in place, or might divert elsewhere.In the former case it is likely that a valve would be required toprevent the escape of fuel vapour. It should be noted at this pointthat, with nozzle engagement structure 20 providing a mechanism forturning fuel filler cap 14, the cap body 18 of fuel filler cap 14 is nolonger strictly necessary, and may in some minimal cases be completelyabsent. However, for most practical cases it will be maintained.

Referring now to FIG. 3, a fuel filler cap 14 is provided according to asecond embodiment of the invention. As above, fuel filler cap 14comprises a threaded section 16, a cap body 18 and a nozzle engagementstructure 20. In this embodiment, fuel filler cap 14 further comprises apair of sloped handles 24. These handles 24 have a similar shape andfunction to some security screws, in that the handles 24 are designedsuch that fuel filler cap 14 can be easily screwed into a car's fuelfilling aperture by hand, but they do not provide suitable purchase forremoving fuel filler cap 14 by hand. This provides a cap that, in theabsence of ridging etc. on cap body 18, encourages the use of a fuelpump nozzle to remove fuel filler cap 14, but then provides a simple wayof replacing fuel filler cap 14 by hand. FIG. 3 shows handles 24 asbeing located on the face of fuel filler cap 14, as may be suitable foruse in a fuel filler system wherein the face of cap body 18 is flushwith the fuel filler aperture or car body when secure. Alternatively,sloped handles 24 may be present on the circumference of cap body 18.Such an arrangement would likely be incompatible with the flush-fittingcap body 18 described, however.

Sloped handles 24 have a structure and function similar to that of aratchet. They have an upright side that, in this case, has a facepointing in a counter-clockwise direction (when looking at the face ofthe fuel filler cap 14) for receiving a clockwise force. The sloped side(which points in a clockwise direction from the apex of the handle 24)forms a more acute angle at its far end and is more difficult to applyforce against. In different embodiments of the invention, there may befewer or more than two handles 24. Furthermore, the ratchet-like handles24 may be hidden by a second cap that covers them and is equipped withcomplimentary ratchets on the inside. This second cap would thenreplicate the feature of being turnable by hand to screw in fuel fillercap 14, but would not provide purchase for unscrewing fuel filler cap 14by hand.

In a third embodiment of the invention (not pictured), nozzle engagementstructure 20 may be equipped with (or mounted on) a ratchet, or similarratcheting means. This provides a method of removing fuel filler cap 14from the car without having to perform a full rotation of the fuel pumpnozzle, which can be awkward when the fuel pump nozzle is connected to abulky hose.

Referring now to FIG. 4, a fuel filler cap 14 is provided according to afourth embodiment of the invention. As above, fuel filler cap 14comprises a threaded section 16 and a cap body 18. In this embodiment,nozzle engagement structure 26 is recessed into the cap body 18 (and mayalso extend into threaded section 16 if necessary). Nozzle engagementstructure 26, in conjunction with cap body 18, defines a recessedcircular channel for fitting the nozzle body of a fuel pump nozzle.There is further a sensing port engagement hole 28, being an indentationinto the head 26 which fits into the nozzle channel of a fuel pumpnozzle, for engaging with the sensing port of a fuel pump nozzle. Thisembodiment provides a mechanism allowing similar methods of removingfuel filler cap 14, i.e. by using a fuel pump nozzle, without having aprotruding nozzle engagement structure that is easy to damage and mightinterfere with the closing of the fuel filler cover. Furthermore, thiscan provide a simple fuel filler cap that can engage with an unleadedpetrol fuel pump nozzle and not a diesel fuel pump nozzle, as thecircular channel can be made too small for fitting a diesel nozzle.Slotting the nozzle into a hole may also be easier for some people thanfitting it over a protrusion. To facilitate insertion of the nozzle, thecircular recess may have a chamfered or tapered entry area. Thischamfering or tapering may also be useful in the case of a protrudingnozzle engagement structure.

In this embodiment, nozzle engagement structure 26 has a similar outerdiameter to that described in the first embodiment, depending on whatnozzle it is designed to engage with. The channel that fits the nozzlebody has a thickness of between 2.3 mm and 5 mm, and preferably between2.5 mm and 4 mm, and more preferably 3 mm. This preferred value shouldbe sufficient to fit either an unleaded petrol nozzle or diesel nozzle.Sensing port engagement hole 28 has to be of a suitable size toaccommodate the sensing port, and so has a depth (radial indentationaway from the outer edge of the nozzle engagement structure) of at least5 mm. Sensing port engagement hole 28 also has a circumferential extentsimilar to that described in the first embodiment, depending on theouter diameter of the nozzle engagement structure and the nozzle it isdesigned to engage with.

Referring now to FIG. 5, a fuel filler cap 14 is provided according to afifth embodiment of the invention. The difference between thisembodiment and the one pictured in FIG. 4 is that there is more than onesensing port engagement hole 28 (four are pictured, this could be anynumber). This results in a nozzle engagement structure 26 that canengage a fuel pump nozzle in a variety of different angles or attitudes.This was a potential problem with other embodiments which could onlyengage the fuel pump nozzle at one angle, as this could result in havingto twist the fuel pump nozzle into a difficult angle in order to firstengage with the fuel filler cap, this task being further complicated bythe often heavy fuel hose.

One requirement that limits the number of sensing port engagement holes28 that it is possible to have in a nozzle engagement structure, is thatthe intervening lobes between the holes must be strong enough towithstand the turning force. More particularly, the lobes that protrudebetween the sensing port engagement holes are used to transmit theturning torque from the fuel pump nozzle to the fuel filler cap 14, andmust be large enough to withstand the force. The size that will benecessary depends on the strength of the material from which they aremade.

Referring now to FIG. 6, a fuel filler cap 14 is provided according to asixth embodiment of the invention. As with the first and secondembodiments, there is a protruding nozzle engagement structure 30.Unlike the first and second embodiments, the nozzle engagement structure30 is solid rather than hollow, giving it a stronger structure oralternatively allowing it to be made of a weaker material whilstretaining the same strength. Such a solid nozzle engagement structure 30is also likely to be harder to damage by any “near misses” of the fuelpump nozzle on the approach. As in the fifth embodiment of theinvention, nozzle engagement structure 30 can accommodate the sensingport of a fuel pump nozzle in any one of four positions, meaning thatthe amount by which the fuel pump nozzle needs to be twisted in order toengage with nozzle engagement structure is reduced. Such a structurealso provides an alternative to the ratchet mechanism described in thethird embodiment—the function can be replicated by removing andreplacing the fuel pump nozzle in a different angle, allowing fuelfiller cap 14 to be removed without having to turn the fuel pump nozzlethrough 360°. In this embodiment, nozzle engagements structure 30 hassimilar dimensions to those of the nozzle engagement structures of thefourth and fifth embodiments.

FIG. 7 shows a seventh embodiment of the invention with very similarstructure to the sixth embodiment. In this embodiment, nozzle engagementstructure 32 is not a large protruding solid that substantially fillsthe nozzle channel of a fuel pump nozzle, but instead a more “minimal”structure, consisting of two sheet-like members, or “blades”, in an “X”configuration. As with the sixth embodiment, this nozzle engagementstructure 32 provides four locations for engaging the sensing port of afuel pump nozzle, however the more open structure means that rather thanclosely following its shape the sensing port is more widelyaccommodated, providing a wider range of angles in which the sensingport can be fitted and thus making it easier to engage with a fuel pumpnozzle. Upon turning a fuel pump nozzle engaged with nozzle engagementstructure 32, the sensing port will shortly come into contact with oneof the “blades” of the structure and thus allow the fuel filler cap 14to be turned by the fuel pump nozzle.

In this embodiment, in order to exclude the possibility of an unleadedpetrol fuel pump nozzle engaging with nozzle engagement structure 32, atleast one of the “blades” that constitute it should be too large to fitinside an unleaded petrol fuel pump nozzle. This results in one of theblades having a length of between 17.5 mm and 19.5 mm, and preferablybetween 18 mm and 19 mm, and more preferably 18.5 mm (the minimum valueof 17.5 mm rather than 17 mm allows for slight variations in the size offuel pump nozzles, and prevents the possibility of an unleaded petrolfuel pump nozzle being forced into engagement). If nozzle engagementstructure 32 is to engage with an unleaded petrol nozzle, the bladesmust obviously have a length of less than 16.5 mm, and preferably inexcess of 12 mm for engaging well with the sensing port. Preferably, theblades have a length of between 14 and 16.5 mm, and more preferably 15.5mm.

It should be noted at this point that only one blade could be used inthis embodiment. Such a fuel filler cap is shown in FIG. 10. In thisfigure, fuel filler cap 14 comprises a single blade nozzle engagementstructure 33, shown as a three-dimensional blade rather than atwo-dimensional sheet as in FIG. 7. In this case, the fuel pump nozzleengaged with nozzle engagement structure 33 would normally need to beturned further before the sensing port engaged the blade and fuel fillercap 14 could begin being turned by the fuel pump nozzle. It is alsopossible that any number blades could be used (including odd numbers),so long as the space left between them was sufficient to fit a sensingport. In the case of an odd number of blades, the blades may extend fromthe centre of fuel filler cap 14 where they meet, rather than from oneedge of the nozzle engagement structure to the other. Furthermore, it ispossible that this nozzle engagement structure could be recessed intothe cap body 18 in a similar manner to the fourth embodiment.

FIG. 8 shows an eighth embodiment of the invention, with a substantiallydifferent nozzle engagement structure, comprising two separate anddifferent components. Fuel filler cap 14 has a nozzle engagementstructure 34 that is similar to the nozzle engagement structure of thefirst embodiment (but is shown in FIG. 8 as having a larger interruptionfor clarity). Fuel filler cap 14 further comprises sensing portengagement structure 36. Unlike the hole-like structures foraccommodating the sensing port of a fuel nozzle in previous embodiments,post-like sensing port engagement structure 36 is designed to fit in tothe sensing port channel. This provides a different mechanism forengaging with the sensing port of a fuel pump nozzle, and fortransferring torque therefrom to the fuel filler cap 14.

In order to fit inside a diesel fuel pump sensing port, sensing portengagement structure 36 has a diameter of approximately 2.5 mm. In orderto fit within a diesel fuel pump nozzle and exclude an unleaded petrolfuel pump nozzle, the distance between the outermost edges of thesensing port engagement structure 36 and nozzle engagement structure 34is between 17.5 mm and 19.5 mm, and preferably between 18 mm and 19 mm,and more preferably 18.5 mm. Furthermore, in order to exclude thepossibility of an unleaded nozzle fitting over just one or the other ofnozzle engagement structure 34 and sensing port engagement structure 36,nozzle engagement structure 34 preferably extends over an arc such thatthe widest measurement across it is at least 17 mm. If the fuel fillercap is to engage with an unleaded petrol fuel nozzle, the sensing portengagement structure has a similar diameter, and the distance betweenthe outermost edges of the sensing port engagement structure 36 andnozzle engagement structure 34 is between 12 mm and 16.5 mm, andpreferably between 14 mm and 16.5 mm, and more preferably 15.5 mm.

FIG. 9 shows a ninth embodiment of the invention. In this embodiment,fuel filler cap 14 comprises a segmented nozzle engagement structure 38,which is round and has a similar outer diameter to the first embodimentfor fitting inside the nozzle channel of a fuel pump nozzle, dependingon which nozzle it is to fit. The segments are shown as being pie-likeslices, but other configurations of segments are also possible. Each ofthese segments is mounted on a spring or other resilient means, suchthat when a fuel nozzle is placed over nozzle engagement structure 38the sensing port pushes down one or more of the segments. This enablesthe fuel nozzle to be placed over the nozzle engagement structure 38 inthe normal way at any angle. After the nozzle is pushed over the nozzleengagement structure 38, upon turning the nozzle the sensing port willcome into contact with the side of one of the remaining segments, whichallows torque to be transferred and the nozzle to be used to turn fuelfiller cap 14. This embodiment provides a nozzle engagement structurethat, although more mechanically complicated than the nozzle engagementstructure of previous embodiments, is extremely simple to use as itadapts to the angle at which the nozzle is engaged with it.

A potential problem of the above described embodiments could occur whentrying to remove a fuel filler cap when not at a fuel pump, for examplewhen refueling a petrol lawn mower or partially filling a car's fueltank after it has broken down due to lack of fuel. In order to overcomethis problem, a key could be produced, having a cross section at leastsimilar to that of a nozzle for engaging the fuel filler cap when awayfrom a fuel pump. This key could be sold separately and kept with thevehicle it fits for emergency use, or alternatively supplied withportable fuel containers.

The skilled person will appreciate that, although the above embodimentsdescribe a whole fuel filler cap with an integrated nozzle engagementstructure or head, a separate nozzle engagement structure could bemarketed and sold for retrofitting to fuel filler caps. Such a separatenozzle engagement structure may take the form of a simple attachmentmounted to a fuel filler cap by an adhesive, screws, nails or mechanicalclips, or may require removal of part of the fuel filler cap such as thecap body and replacing it. The separate nozzle engagement structurecould take any combination of the features described above, but mayrequire more substantial modification to the base structure for somefeatures e.g. a hole may need to be drilled into a fuel filler cap tofit a separate nozzle engagement structure similar to that illustratedin FIG. 9.

In the embodiments above, various different features are described inlight of different embodiments. The skilled person will realise that thefeatures from different embodiments can be combined in various ways toresult in different fuel filler caps, e.g. having the nozzle engagementstructure of the first embodiment embedded into the cap body as in thefourth embodiment, also further comprising more than one interruptionfor engaging the sensing port as in the fifth embodiment.

The skilled person will also realise that other structures andconfigurations may be used to implement the nozzle engagement structureor head. In the case of a fuel filler cap for a diesel vehicle, the fuelfiller cap needs one or more structures that protrude into the nozzlechannel of a fuel pump nozzle that do not fit inside an unleaded petrolnozzle but do fit inside a diesel nozzle. In the case of a fuel fillercap for an unleaded petrol vehicle, the structures that fit inside thenozzle will necessarily also fit inside a diesel nozzle, although theymay not engage well with it. In order to ensure the rejection of adiesel nozzle in such a case, there needs to be a further engagementmechanism such as the recess illustrated in FIG. 4 or 5.

It is possible to construct an even more minimal embodiment than a“single blade” variant of the seventh embodiment, comprising two or more“posts” that, measured from furthest edge to furthest edge fit inside adiesel nozzle but not inside an unleaded fuel nozzle. Such an embodimentcould be viewed as having the nozzle engagement structure of the firstembodiment with two or more large interruptions, or having the nozzleengagement structure of the fifth embodiment in which the sensing portengagement holes have a radial depth such that they meet in the middle.However, such a “post” embodiment is not very practical, as the postswould need to be particularly strong in order to withstand the turningforces due to their small size, and it would be possible to place anunleaded petrol nozzle over only one of the posts and perhaps use thenozzle to unscrew the fuel filler cap in such a situation.

FIG. 11 shows a further fuel filler cap 14. The cap 14 has a lid 40,which is adapted by way of indentations 42 to act as a handle for thecap as a whole. The cap 14 further comprises a body 43 onto which thecap 14 is mounted. The body 43 comprises the fitting for securing thecap in a fuel filling aperture, illustrated here as a screw thread thatscrews the cap into the aperture on turning the cap clockwise.Alternatively, as described above, this fitting may be of the bayonettype or any other appropriate fitting. Depending on the requirementsimposed by safety and reliable operation of the vehicle, the body maycontain various valves to permit venting of excess pressure on one sideor the other of the cap, or valves for sealing the cap in the event ofan accident.

Lid 40 is rotatably coupled to the body 43 of the cap 14, such that inits rest state the lid may be freely rotated without exerting asignificant force on the body, thus rendering the lid inoperable fortightening or loosening the cap in the fuel filling aperture.

The cap further comprises a recessed nozzle engagement structure 46comprising an annular channel 45 with a radial extension 47 toaccommodate the sensing port of a fuel nozzle. This nozzle engagementstructure is comparable to that shown in FIG. 4.

The nozzle engagement structure in this embodiment is designed to engagewith a diesel nozzle and not a petrol nozzle. The central head of thenozzle engagement structure has a diameter at its widest point that istoo large to fit inside a petrol nozzle. At the base of the annularchannel there is a trigger 44, which is exposed in FIG. 12. When thetrigger 44 is pressed, for example by a diesel nozzle that has engagedwith the nozzle engagement structure 46 and fit into the annular channel45 in which the trigger is located, a mechanism (described below) isengaged that more firmly couples the lid 40 to the body of cap 14. Theengagement of this mechanism means that the lid 40 can now be used tounscrew the cap 14, permitting access to the fuel filling aperture forfuelling the car to which cap 14 is fitted.

The apparatus described above provides a simple and user-friendlymechanism for preventing misfuelling of cars. Upon arriving at a petrolstation the user need simply press the nozzle they intend to use to fuelthe car into the nozzle engagement structure 46 to activate the cap sothat it can be removed. If the user has selected an inappropriatenozzle, such as an unleaded petrol nozzle, they will not be able toactivate the cap and thus will be unable to fill the vehicle with theincorrect fuel. After activating the cap by this simple pressing action,the user is able to remove the fuel filler cap 14 by hand, in the usualway. The mechanism that engaged the lid 40 with the cap body is arrangedto disengage when a certain tightening torque is exceeded, meaning thatthe cap will automatically return to its rest state in which the lid 16is disengaged from the body 43 upon being screwed back in, ready forrepeat use.

The cap 14 may further comprise a lock 48 for securing the cap toprevent e.g. theft by the siphoning of fuel. This may be particularlydesirable on cars in which the fuel filler cover is not automaticallylocked by the car. This lock may be used to prevent the opening of thecap 14 by preventing the lid 40 from engaging with the body, meaningthat purchase cannot be obtained in order to remove the cap 14.

FIG. 12 shows the internal structure of cap 14. The trigger 44 is shownwithout the nozzle engagement structure. As will be shown more clearlyin later Figures, the top of trigger 44 is sloped such that pushing afuel nozzle into the nozzle engagement structure will tend to maketrigger 44 move under a camming action laterally towards the centre ofthe nozzle engagement structure. The trigger is equipped with biasingmeans adapted to provide a resistive force to this motion and return thetrigger to its original location after the nozzle is removed.

Referring now to FIGS. 12 and 13, the mechanism of the cap 14 includesan arm 50. The arm has a generally central pivot 52 having an axisapproximately parallel with the axis of rotation of the lid 40. Thispivot is attached to the underside of the lid 40, towards the edge ofthe lid. The arm is equipped with biasing means coupled to one end ofthe arm for pushing the other, distal end of the arm towards the outsideedge of the lid 40. In the configuration shown in FIG. 12, the arm isunable to move in response to biasing force because the trigger 44 isholding the arm in place. The trigger 44 fits into a recess 55 in thehead of arm 50, therefore preventing the arm from pivoting while thetrigger is within the recess. When a nozzle is introduced into thenozzle engagement structure, trigger 44 is pushed away from the arm 50and leaves the recess 55, freeing the arm to rotate around the pivot 52in response to the biasing force. This causes a protruding finger 56 tocome into contact with and engage within a ratchet track 58 that runsaround the inside edge of cap 14.

Whilst the arm 50 and trigger 44 are both coupled to the lid of the cap14, the ratchet track 58 is joined to the body 43 of the fuel fillercap. Therefore, by pressing the trigger and releasing the arm, aconnection is created between the lid and the body of cap 14 allowing atorque to be transferred between the two components and activating thecap so that it can be removed by turning the lid.

It should be noted that the pressing of the trigger need not becontinuous since once it has been pressed, the arm 50 no longer engagestrigger 44 and will remain in place until it jumps out of engagementwith the ratchet track 58 as described below.

The ratchet track 58 and finger 56 are arranged so as to preventslipping when turning the lid clockwise, which in most vehicles is thedirection one turns a fuel filler cap to tighten it. The construction ofthe ratchet track 58 means that when tightening the fuel filler cap, ifthe torque applied to the lid exceeds a certain amount then the arm 50will jump out of contact with the ratchet track and be re-captured bythe trigger 44, therefore disengaging the lid from the body of the cap.This reproduces the commonly found ratchet feature in current fuelfiller caps that prevents over-tightening of the cap, as more than acertain amount of resistance to turning the body of the cap in theaperture will trigger this disengaging mechanism.

The shape of the ratchet track and arm, and the biasing forces on thearm and trigger, can be selected such that the disengagement torquerequired to trigger the disengagement of finger 56 and ratchet track 58is less than the maximum torque which can be applied when unscrewing thecap without the arm slipping, therefore avoiding the situation where theratchet track allows the cap to be screwed into a fuel filler aperturetighter than can be removed with the purchase offered by the cap.

As depicted in FIGS. 12, 13 and 14, arm 50 further comprises a lockingpost 60 for fitting in a locking ring 62. The locking post 60 protrudesbelow the arm 50 and is long enough to fit within the hole 64 of thelocking ring 62, which is also situated below the arm 50. The lockingring is attached to the lock 48 of the cap. The locking ring defines ahole 64 having a wide end 66 and a narrow end 68. The locking ring 62 isdepicted in FIG. 12 as being in a locked position. In this position,locking post 60 is tightly held within the narrow end 68 of the lockingring hole 64 and the arm is actually unable to pivot around pivot 52 asdescribed above. On turning the lock anti-clockwise through a rightangle, for example, using a key, the locking post 60 will be located inthe wide end 66 of the locking ring hole 64, which allows the arm 50 topivot when released by trigger 44.

Referring now also to FIG. 15, the relationships between arm 50, trigger44 and locking ring 62 can be more clearly understood. The trigger 44and its complementary recess 55 can be seen in relation to each other.The sloped top of trigger 44 that causes it to move to one side whenpressed by a nozzle is clearly visible. The locking post 60 and lockingring hole 64 are shown in a locked relationship; with the locking post60 being directly above the narrow end 68 of the locking ring hole 64.

Referring now also to FIG. 16, the fuel filler cap 14 is shown with thelocking ring 62 in its unlocked position. The locking ring 62 has beenrotated 90° anti-clockwise. The locking pin 60 is now located in thewide end 66 of the locking ring hole 64, so that when the trigger 44 isactivated the arm 50 will be free to rotate around pivot 52 and engageratchet track 58 via finger 56.

FIG. 17 shows the cap 14 in the activated state, in which the lid of thecap (not shown) is coupled to the body of the cap via arm 50 and ratchettrack 58. The arm is shown rotated around the pivot 52, and finger 56 isfirmly engaged with ratchet track 58. As can be seen in the figure,trigger 44 is well clear of the arm 50 and so can be released. It isworth noting at this point that the engagement of finger 56 and ratchettrack 58 will not always occur unaided. In particular, since the arm iscoupled to the lid, which may be freely rotated when in its rest state,the finger 56 may be directly adjacent to a protrusion in the ratchettrack 58 when the arm 50 is released by trigger 44. In such a situationthe arm may become stuck without fully engaging. This problem is easilymitigated by giving the cap a slight twist whilst button 44 is stilldepressed (otherwise, if trigger 44 is released before the twist isadministered, the arm 50 may become secured again in its rest state).This twist is easily carried out using the fuel nozzle whilst it isengaged with the nozzle engagement structure.

An embodiment of a fuel filler cap has been described above, withreference to the Figures. The skilled person will realise that variousmodifications could be made to the embodiment within the scope of theinvention. For example, the locking mechanism described, includinglocking ring and locking pin, may not be necessary in some vehicles.Furthermore, on a vehicle where a fuel filler cap with a lockingmechanism is preferable, the locking mechanism may be implemented usingany other method known to the art, for example by securing the fuelfiller cap to some part of the fuel filling aperture or vehicle body.

The mechanism that couples the lid of the fuel filler cap to the body isdescribed as being activated by a trigger that moves under a cammingmotion. The skilled person will realise that many alternative devicesmay be appropriate for triggering the mechanism contained in the fuelfiller cap, including levers, switches, buttons and the like. Theembodiments above are fuel-nozzle specific by virtue of an engagementstructure dimensionally compatible with diesel nozzles and incompatiblewith unleaded petrol nozzles, the trigger being sheltered within theengagement structure so that it is pressed by a nozzle engaging with thestructure.

Two biasing means are described above, related to the trigger and thearm. The skilled person will realise that these means may be implementedby a variety of devices such as springs, rubber bands or resilientplastics built into the cap as a whole. Furthermore, these biasing meansmay be arranged so as to work in tension or compression. The biasingmeans may also be coupled to other parts of the components from thosedescribed without affecting the operation of the invention. For example,the arm is described above as having a biasing means coupled to one endof the arm, distal from the finger for engaging with the ratchet track.The skilled person will realise that biasing means could alternativelybe coupled to the end of the arm having the finger without materiallyaffecting the operation of the invention.

The cap as described above has two states: a rest state and an activatedstate. During the rest state, the lid is rotatably coupled to the bodyof the cap so that it is not useful for exerting a significant torquefor unscrewing the cap. When activated, the lid and body are firmlycoupled such that the lid may be turned to unscrew the cap. The lid maycover the entire upper or external surface of the cap, or alternativelymay be an annular or ring-shaped handle component that encircles thebody of the cap on its circumference and hinders a rotating force beingexerted on the body of the cap by preventing a force being applied tothe circumference of the body directly.

In an alternative embodiment, the lid of the cap may be coupled to thefuel filling aperture or vehicle body in its rest state. This preventsrotation of the body by turning the lid similar to that above, althoughin this embodiment because the lid cannot be rotated. On activating thecap, the lid may then be decoupled from the aperture or vehicle body sothat the cap may now be removed. This embodiment may be realised in adirectly analogous way to that described above, with one of themechanisms components (for example, the arm or ratchet track) beingcoupled to the lid and the other to the body of the vehicle or fuelfilling aperture.

The cap is described as having a mechanism for rigidly coupling the lidto the body of the cap in its activated state. One embodiment of such amechanism is described. However, the skilled person will realise thatother mechanisms may be used to selectively couple the lid to the bodyof the cap. For example, the components of the mechanism as describedabove may be reversed, with a ratchet track of some sort being activatedby the trigger, for example, causing regular protrusions to pop up, forengaging with an arm coupled to the body. Alternatively, substantiallydifferent ratchet mechanisms may be appropriate, such as a mechanismhaving ratchets with faces that are substantially parallel to the planeof rotation of the cap that are activated by pressing one towards theother in an axial direction. Other appropriate mechanisms may operate ina similar manner to a bolt and socket, for example the body having acomponent analogous to a bolt with the lid having a component that fitsaround or otherwise engages with the bolt when activated.

The nozzle engagement structure described above is designed so as to fita diesel nozzle and exclude an unleaded petrol nozzle, by virtue of thesize of the head that fits into the nozzle channel. Appropriatedimensions for the head, as well as the annular channel around it, arediscussed above. A nozzle engagement structure for engaging an unleadedpetrol nozzle and excluding a diesel nozzle would have an annularchannel with an outer radius too small to accept a diesel nozzle. Again,suitable dimensions to achieve this end are described above.

The skilled person will realise that the different aspects of theembodiments described above may be combined with each other to make newarrangements not specifically disclosed. Furthermore, as mentionedabove, there may be alternative aspects available to the skilled personnot described here. The embodiments described above are descriptive, andshould not limit the scope of the invention. The scope of the inventionshould only be defined by the appended claims.

1. A fuel filler cap comprising: a body for fitting in a fuel fillingaperture; a handle rotatably coupled to the body; coupling means forselectively coupling the handle to the body for rotating the body byrotating the lid; and a trigger for activating the coupling means.
 2. Afuel filler cap according to claim 1, further comprising nozzlediscrimination means for discriminating between nozzles having differentproperties, wherein the trigger is associated with the nozzlediscrimination means for being activated by an appropriate nozzle.
 3. Afuel filler cap according to claim 2, wherein the nozzle discriminationmeans comprises a circular channel having appropriate dimensions forreceiving a nozzle, and the trigger is located in the bottom of thechannel for being activated by a nozzle entering the channel.
 4. A fuelfiller cap according to claim 3, wherein the trigger comprises a faceoriented so that it faces towards the top of the channel, the face beingsloped for moving laterally under a camming action when pressed by anozzle entering the channel.
 5. A fuel filler cap according to anypreceding claim 1, wherein said coupling means comprises an annularratchet member and an arm for selectively engaging with the annularratchet member.
 6. A fuel filler cap according to claim 5, furthercomprising a resilient member for biasing the arm towards the annularratchet member; wherein: the trigger is moved by a nozzle engaging withthe nozzle discrimination means; the arm comprises a head for engagingwith the trigger; the trigger and the head being arranged so that whenthey are engaged the arm is not engaged with the annular ratchet member;further wherein: the movement of the trigger caused by the nozzle causesthe trigger to disengage from the arm, allowing the arm to move towardsthe ratchet member.
 7. A method for removing a fuel filler cap from afuel filling aperture using a fuel pump nozzle, the fuel filler capcomprising nozzle engagement means; the method comprising: engaging thefuel pump nozzle with the nozzle engagement means; and turning the fuelpump nozzle to remove the fuel filler cap.
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